AP EAPCET 06-Jul-2022 Shift 2 Paper

At null point (and along the axis), earth's magnetic field and bar's magnetic field are opposite in direction.
- On equitorial line, bar's magnetic field is opposite in direction to its field on the axis. Hence, on equatorial line, the two fields add up As null points are on the axis of the bar magnet, therefore,
B1=‌

µ0

4π

‌

2M

d3

=H
on the equitorial line of magnet at same distance (d), field due to the magnet is
B2=‌

µ0

4π

‌

M

d3

=‌

B1

2

=‌

H

2

Therefore, total magnetic field at this point on equitorial line is
B=B2+H=‌

3H

2

=‌

3

2

×H
Since, given B=0.69
0.6=‌

3

2

×H⇒H=‌

0.6×2

3

=0.4G